Production of magnetic sound tape



C. SPEED ET AL PRODUCTION OF' MAGNETIC SOUND TPE May 15, 1956 6 Sheets-Sheet l Original Filed Dec.

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May 15, 1956 w. c. SPEED ET AL PRODUCTION oF MAGNETIC souND TAPE 6 Sheets-Sheet 2 Original Filed Dec,

INVENTORS W/LL/AM C. P550 YJAMEs I Dwyer? ATTO RNE V5 May 15, 1956 w. c. SPEED ET Ax.

PRODUCTION oF MAGNETIC SOUND TAPE 6 Sheets-Sheet. 3

Original Filed Dec.

A T TGRNEYS May 15, 1956 w. c. SPEED ET AL 2,745,605

PRODUCTION OF MAGNETIC SOUND TAPE Original Filed Dec. 29, 1951 6 Sheecs-Shee:l 4

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May 15, 1955 w. c. SPEED ET AL 2,745,605

PRODUCTION OF MAGNETIC SOUND TAPE Original Filed Dec. 29, 1951 6 Sheets-Shea nnnnnnn n nnnnn nn VENTORS W/LL/AM BPEED J'AMEBSYJ D14/VER ATTORNEYS PRoDUcTroN oF MAGNETIC SOUND TAPE William C. Speed, Riverside, and .lames J. Dwyer, Stamford, Conn., assignors to Audio Devices, Inc., New York, N. Y., a corporation of New York Continuation of applications Serial Nos. 264,181 and 264,182, December 29, 1951. This application December 29, 1951, Serial No. 264,139

1 Claim. (Cl. 242-55) magnetic sound recording tape, including the splicing of the tail end of a roll of tape base undergoing processing to the forward end of a roll of tape base next to be processed to provide a continuous production operation.

A number of diiculties arise in processing successive rolls of tape base in the customary way. Time and labor are required to string or feed the forward end of each roll through the coating and drying machines. When the coating step is stopped for this purpose, excess magnetic material spreads over surrounding areas and must be carefully removed. Preliminary tests on some of the tape base must be conducted until normal coating operations are restored. Objectionable amounts of tape base and magnetic material necessarily are lost. v4f

As a result of our investigation we have discovered that as many rolls of tape base as desired may be processed successively, the tape base of one roll following that of another roll in a continuous path of travel so that Vthe coating step itself proceeds without interruption. The tape base strings and feeds itself automatically through the coating and drying machines.

The features of the invention will be better understood by referring to the accompanying drawings, taken in conjunction with the following description, in which Fig. 1 is a plan view of a piece of tape base, specically of the moving picture 35 mm. film type, coated with i'lnely divided magnetic material;

Fig. 2 is a plan view of an apparatus illustrative of a l practice of the invention, showing a tape base unwinding device, a cleaning device, a preliminary drying machine,

a coating machine, a nal drying machine, a winding device, and a splicing device;

Fig. 3 is a section of the line 3 3 of Fig. 2, showing a sectional view of the over-all drying machine;

Fig. 4 is an enlarged section on the line 4--4 of Fig. 2, showing a side sectional view of the unwinding and cleaning devices; l

Fig. 5 is an enlarged section on the line 5 5 of Fig. 4, showing a top view of the unwinding and cleaning devices;

Fig. 6 is a section on the line 6 6 of Fig. 4, showing a partial end View of the cleaning device;

Fig. 7 is a section on the line 7 7 of Fig. 4, showing a top view of the bottom portion of the cleaning device;

Fig. 8 is a section on the line 8 8 of Fig. 4,V showing a driving pin to t in one of a plurality of circumferentially spaced pockets in the hub of a half-reel of the unwinding device;

Fig. 9 is a section on the line 9 9 of Fig. 4, showing a plurality of sprockets mounted on a drive shaft, for advancing the tape base in its path of travel;

2,745,605 Patented vMay 15, 1956 Fig. 10 is a section on the line 10 10 of Fig. 4, showing a drive motor and a speed regulator associated with the `drive shaft;

Fig. 1l isa section on line 11 11 of Fig. 2, showing a sectional end view of the coating machine;

Fig. 12 is a section on the line 12 12 of Fig. 11, showing a sectional side view of the coating machine;

Figs. 13 and 14 are sectional views on the lines 13 13 and '14 14,'re7spectively, of Fig. 11, showing adjusting means for therfered hopper of the coating machine;

Fig. 15 is a section on the line 15 15 of Fig. 11, showing tension means (see also Figs. 11 and 12) for Vthe coated tape base, spliced and unspliced, as it moves through and away from the coating device;

Fig. 16 is a longitudinal sectional sideview on the line 16 16 of Fig. 17; Fig. 17 is a longitudinal top view on the line 17 17 of Fig. 16, and Fig. 18 a cross-sectional view on the line 18 18 of Fig. 17, showing the tape base as it advances under the feed hopper over a bottom sup- Port;

Fig. 19`is an enlarged section on the lines 19-19 of Figs. 2 and 20, showing a side interior view of the tape base discharge portion of the drying machine andthe coated tape base winding device;

Fig. 20 is a partial plan view of Fig. 19, with a top window removed from the drying machine to show the interior thereof at the discharge end portion, as well as to show the top of the winding device;

Fig. 21 isa section on the line 21 21 of Fig. 22; and

Fig. 22 is a section on the line 22-22 of Fig. 21, showing enlarged views of tension driving andV guide means for the coated tape base at the discharge end (Figs. 19,

20) of the drying machine;

Fig. 23 is a section on the line 23-23 of Fig. 19, show-A ing brake adjustment means for the drive belt of the winding device;

Fig. 24 is a section on the line 24-24 of Fig. 4, showing a support for the tape base splicing device; l

Figs. 25-29 illustrate steps taken to splice the rearward end of an unwound roll of tape base to the forward end Y of a wound roll of tape base about to be processed;

Fig. 25 is a perspective View of a at adhesive splicing V band, with temporary protective covers on both sides;

Fig. 26 is a longitudinal sectional view showing the forward end of a wound roll of tape base on the splicer j and with the splicing band, lower cover removed, placed Y thereon;

Fig. 27 is a section on the line 27 27 of Fig. 26,;-

Fig. 29 is a section on the line 29 29 of Fig. 28, showing the latter assembly mounted in the splicing device;

Fig. 30 is a plan view of the cut-olf spliced tape base after it has served its purpose to thread the second roll through the cleaning device, the over-all drying machine and the coating machine, corners being cut away to show the interior portions of the spliced area; and

Fig. 3l is a section on the line 31 31 of Fig. 30, showing a side view of the same splice.

Reference may be made rst to Fig. 2 for a general over-all layout of the apparatus. It is divided into the following: 1) a tape base unwinding zone A; (2) a cleaning zone B; (3) a preliminary drying zone C; (4) a coating zone D; (5) a final drying zone E; (6) a winding zone F; (7) a splicing zone G; (8) a slack-producingv zone H; and (9) a spliced-portion cut-out zone I.

In terms of apparatus, the zones may be regarded in ing device', a splicing device 52, and a slack-producing device 54.

They shall be taken up in that order. It will be clear that the preliminary and the final drying machines may be regarded as one and the same machine, although they could, of course, be separate from one another. This is true also of the cleaning and slack-producing devices. The spliced-portion cut-out zone need not be provided with special apparatus, a pair of shears only being advisable.

Unwz'ndng device Going first, therefore, to tape base unwiuding device 40, reference is made to Figs. 2, 4, and 8. It includes a rearwardly extending back side arm 60 to the top of which a pair of spaced journals 62 and 64 are secured. The journals are fitted with shafts 66 and 68, fitted at their rear ends with brake-discs 70 and 72, respectively. The discs Vare recessed to accommodate exible brake bands 74 and 76, the ends of which are secured to a tension spring 78, the tension being regulated to provide an optimum band pressure on the discs.

The forward ends of the shafts are secured to halfreels 80 and S2 adapted to hold rolls of tape base, the forward flat faces of which are provided with pocket-pins 84 and S6 and tapered ends 88 and 9i). The tapered shaft ends fit into complementary shaft holes of hubs 92 and 94. The hubs are provided with a plurality of circumferentially spaced pocket-holes 96 adapted to receive the pocket-pins of the half-reels. This arrangement of pins and pocket-holes permits easy placement of tape-base loaded hubs on the tapered shaft ends for unwinding and easy removal of the hubs when unloaded. As shown in Fig. 4, hub 92 is almost unloaded or empty, tape base 100 still being fed therefrom to cleaning device 42. Hub 94 is loaded with a roll of tape base 102 awaiting its turn to be fed to the cleaning device when hub 92 is unloaded. Thesplicing of the two pieces of tapebase will be described below.

Cleaning and slack-producing devices cess to the tank. On leaving hub 92 (or 94), tape base Y 100 (Fig. 4) passes over the top and downwardly along a roller 120 mounted on a lateral shaft supported by a bracket 122 (Fig. 5) attached to rearwardly extending arm 60. A number of similar rollers are used throughout the apparatus. They have side flanges, like sprockets, but no teeth and act primarily as guides. This assembly is located directly above an inlet 124 in an offset portion of the tank. c j

The bottom interior (Fig. 4) of the tank is fitted With a pair of spaced bottom rollers 126 Vand 128 rotatably mounted (Fig. 7,) between a pair of spaced side supports 130 and 132 with end legs 134 and 136 (Fig. 4) normally resting by gravity on the interior bottom of the tank. This roller assembly 138 (Fig. 4) is movable as a unit up and down the Vtank within the cleaning liquid. The tape base passes downwardly through a body of cleaning liquid 140 maintained at a normal level 142, around first bottom roller 126, rises to and moves around a housing roller 144 mounted on a lateral shaft supported by a bracket 146 Y (Fig. 5) extending through the rear of the housing, attached to arm 60; similar to roller 120 in the same plane exteriorly of the housing.

The tape base then descends (Fig. 4) to and around second bottom roller`12S, described above; thence upwardly between a lower pair of spaced air-squeegees 159 andl 152 in the form of lateral pipes, closed at their forward'ends, connecting at their rear ends with an air distributing chamber 154 (Fig. 5) attached to the rear Wall of the housing. The chamber connects, in turn, with a compressed air coduit 156. The air-squeegees are pro- `water, preferably with a detergent added thereto.

vided with small transverse slits or holes 15S and 16,0l slightly below a plane passing horizontally through their centers, so that currents of air are directed downwardly against wet cleaned tape base 19d as it rises between the squeegees, thus forcing and directing liquid on both sides of the tape base downwardly toward and into the main body of cleaning liquid. The tape base, thus partially dried, rises to and passes between an upper pair of similar air-squeegees 162 and 164, similarly secured to the airdistributing chamber, and similarly provided with small transverse slits or holes. The rising tape base is thus subjected to a double air blast on both sides to assure the removal of excess cleaning liquid.

Any suitable cleaning liquid may be employed, such as The cleaning solution or compound should be one that does not attack, and therefore damage, the particular tape base being used. Among the cleaning compounds are carbon tetra-chloride, tri-chlor-ethylene, toluol, de-greasing agents, etc. t

The cleaned and partially air-dried tape base rises (Fig. 4) through the top of the housing to and around a roller 166 mounted above the far left of the housing in a bracket 168 secured to arm 6).

During its transit through the cleaning device, tape base is given a thorough cleaning. Augmented cleaning action is obtained as the tape base moves rapidly through and hence in frictionable engagement with the body of cleaning liquid, which in turn is kept in a continuous state o-f agitation that in itself exerts a washing effect. In addition, each portion of the moving tape base is in wiping engagement successively with the three rollers. This is true particularly of the side of the tape base to be coated. It receives at least two such wipings against the bottom rollers. More rollers and more airsqueegees may be employed, if desired. The moving tape base may be caused likewise to slide against fixed wipers, not shown, in the body of cleaning liquid. The air under pressure escaping from the two pairs of air-squeegees of course also exert a cleaning action on both sides of the tape base.

As more particularly shown in Figs. 4 and 5, ample provision is made for the escape of used air and cleaning liquid vapors. Thus, a baffle plate 170 attached to the rear wall of the housing extends forwardly adjacentto and slightly beyond the air squeegees, thus forcing the used air to pass around the forward end, under the bottom and over the top, of the baiiie plate. Such air then finds its way into lateral conduit 172 (Fig. 5) and up right vent-pipe 174, by forced draft, to the outside atmosphere.

This forced draft is utilized also to carry vapors from the cleaning liquid, which could, in some cases, be harmful or obnoxious to workmen in the same room, to the outside atmosphere. 176 extends across the rear of the housing, well above the cleaning liquid level, connecting with a hood 178 (Fig. 5) terminating at its top with the vent-pipe.

As noted above, roller assembly 138 is movable as a unit up and down the tank within and out of the cleaning liquid. This is for a number of highly useful purposes. One is to raise the rollers and hence the loops of tape base as its tail or rear end portion is spliced to the forward end portion of a succeeding roll of tape base,. as will be described in more detail below. Another is to raise the rollers and hence the loops of tape base above the liquid level when operations are suspended, say for the night, or any other reason, or when it is desired to clean the tank and to replace the old with new cleaning liquid. For the latter purposes the end walls of the tank (Figs. 4 and 6) are provided with complementary holes well above the normal liquid level to receive removable lateral rods 200 and 2412, spaced to span the free space between end legs 134 and 136 and thus to permit spaced side supports and 132 of the roller assemblyv to rest on the rods. As shown in dotted outline 138 in'FigL'kt,"

To this end a filter-passageway.,

the roller assembly is then well above level 142 of the cleaning liquid.

Preliminary and final drying machinesA The cleaned and partially air-dried tape base is then passed (Fig. 4) downwardly, around roller 210 on bracket 212, secured to the laterally extending arm support as before.

Thence the cleaned tape base passes (Fig. 4) into and through the preliminary drying machine 44. Although the tape base passes through that machine and also coating machine 46 before final drying machine 48, since the two drying machines form a more or less unitary assembly, it may be helpful to describe them at this point.

The preliminary and nal drying machines together form a closed elongated box-like structure 214 (Fig. 2) with a bottom (Fig. 3) 21i6, a right end wall 218, (Fig. 2)

a back side wall 220, a left end wall 222, a front side wall 224, and a top 226 (Fig. 3). The top is covered with a plurality of removable windows 228, 230, 232, 234 and 235, for visibility and access. The box-like structure as a whole rests on a frame support 24? (Fig. 3) not wholly shown. Rearwardly extending back side arm 60 is integrally secured to back side wall 220 (Fig. 2).

Referring for the moment to Figs. 3 and 4, it will be noted that an air line with a filter 242, a heater 244, and an inlet 246 connect the central bottom portion of the box-like structure, which is divided horizontally by a perforated partition 248 into a lower over-all heated airdistributing chamber 250 and an upper over-all drying chamber 252. A breaching 254 connects the upper front side of the drying chamber with a stack 256, having a damper 258, for the controlled venting of spent drying air to the outside atmosphere.

Also associated with the box-like structure is suitable driving mechanism to pass the tape base through the apparatus as a whole. This mechanism includes (Figs. 4 and l0) a motor 260, a speed-reducer or regulator 262, with a cross drive shaft 264, a lower drive pulley 266 on the end of the drive shaft of the speed reducer, and a drive belt 268 for the right end of the drying machines.

The speed regulator 262 is provided to control the speed of the motor. It includes an upright rod 272 which connects at its lower end with the speed reducer and at its upper end with a bevel gear 274 in mesh with another bevel gear 276, the latter being connected to one end of a laterally extending rod 278 terminating (Fig. 2) in a hand wheel 280 slightly beyond the left end of the box-like structure. The wheel may be turned to reduce or increase the speed of the motor, as desired.

Drive belt 26S (Figs. 2, 4 and 5) at its upper portion fits around an upper pulley 282 secured to the far end of a right cross drive shaft 284 extending horizontally through the upper right hand end portion of the drying chamber. The shaft is supported in journals 286 and 288 (Fig. 2) attached to the frame support. A plurality of sprockets and rollers are mounted on the shaft, the sprockets being integrally and the rollers loosely mounted thereon. Unlike the rollers, the sprockets are provided circumferentially with two rows of sprocket teeth adapted to tit into the sprocket holes of the tape base. In the instant construction, the sprockets and the rollers number ten each, a total of twenty. The former are three far end sprockets 290, 292 and 294 (Fig. 9); four single intermediate sprockets (Fig. 2) 296, 298, 300 and 302; and (Fig. 20) three near end sprockets 304, 306, and 308. The latter are divided into live pairs, 316i-312, S14-316, 3118-320, 322-324 and 326-328. The sprockets and rollers are kept in position on the shaft by end collars 301 and 302.

The upper reft portion of the drying chamber is provided with a left cross shaft 330, suitably supported in journals 332 and 334. It is tted with a plurality of rollers 340, a total of eighteen in the instant construction. They are loosely rnOuntedl on the shaft, beingkeptin properalignf: mentV to avoid lateral movement by collars 342 and 344. No sprockets are used on this shaft becauseffound to be.

unnecessary. The shaft is not power-driven. As will be explained below, the eighteen rollers to the left and the f near nineteen sprockets and rollers to the right complement each other in operating to pass the coated tape base generally back and forth in what amounts to a helical path ,i

of travel.

As already noted, on leaving the cleaning device (Fig. 4), the cleaned partially air-dried tape base passes downwardly to and around a roller 210. The tape base passes .1

through a slot 354 in right end wall 21S into upper over-all drying-chamber 252 and moves around a roller 356 mounted on a bracket 358 attached to back side wall 220. The latter roller is located a short distance forward of and at a slightly lower level than right cross drive shaft 284.

This arrangement (Figs. 4, 5 and 9) helps to place the tape base under suitable tension as it passes around rst far end drive sprocket 290 and is advanced (Fig. 2) longitudinally across the drying chamber to coating machine 46. y

While thus in transit the tape base is in contact with heated air and is dried in readiness for receiving a coating of rnag-Y netic material.

If desired, the cleaned and dried tape base may be given4 a preliminary coating of suitable adhesive material, forVv example, in the manner described in our co-pending application, Serial No. 201,794, filed December 2l, 1950, to ,y

facilitate adherence of the magnetic coating.

Coating machine The coating machine is illustrated in some detail in Figs. 1l-18. As shown in Figs. 2, l1 and 12, it is located in and above an opening 360 in the far left corner portionl remaining two rollers 374 and 376vfollow thereafter. The', first advance roller 362 is mounted below the bottom support, between and intermediate (Fig. 11) the endsof a pair of spaced depending arms 380 and 382 pivotally suspended at their upper ends to a laterally extending rodv 384 secured at its rear end to a bracket 386 attached to. the rear side wall of the drying chamber. Sleeves 388 and 390 separate the arms from each other and sleeve 392 separates the arms from the side wall. The lower ends of the depending arms are connected pivotally (Fig. l2) to a forward-arm 394 the end of which is pivotally connected by means of a pin and slot connection 395 to a lateral-arm 396 extending through the back side wall, being supported intermediate its ends by a pivot 398. A tension spring 400 (Fig. 2) is secured at one end to the outer end portion of the lateral arm and at the other end to a threaded rod 402 extending through a hole in an anchor 404 secured to the back side wall. A lock nut 406 lits on the free end of the threaded rod. The assembly Jiust described is used to fix the position of the first advance roller 362 in the path of travel of the tape base. Movement of the threaded rod toward the right end of the drying chamber causes the roller to move toward the left end of the chamber, and hence to place the advancing tape base under greater tension. The tension may be diminished by moving the threaded rod toward the left end of the drying chamber, when the roller is moved to the right. Spring 400 also keeps the roller under yieldable tension so that it is free to yield a small amount forwardly or rearwardly, as required, while the tape base moves around the roller to the second advance roller.

Second advance roller 364 (Figs. 11 and 12) in the series is located in a fixed position above and to the right of the rst advance roller, but in advance of and below tape base bottom support 372 in the path of travel of the tape base, being supported in spaced journals 410 and 412 attached to the under side of a platform 414 disposed externally of and above the,v drying chamber. The under sidelof Vthe tape base engages and moves' around the right side portion of the roller toward third advance roller l366. The third advance roller (Fig. 12) is located in fixed position slightly in advance of the bottom support, being supported by'spaced journals 416 secured to the top of platform 414. This roller, unlike the preceding roller, en-v gages the upper side of the tape base and depressesit onto the bottom support. The path of travel of the tape base between the two rollers is arched or convex, thus also help ing to keep the tape base under tension as it is coated.

The tape base thereupon moves directly below feed hopper l370, and slides across the arched top surface of bottom support 372 to and partly around fourth roller 374 located below and slightly to the left of the bottom support, the position of the roller being fixed so that the tape basel remains in contact with the bottom support an appreciable distance beyond the feed hopper.

Fifth roller 376 (Fig. 12) is xedly located below and slightly to the left of the preceding roller, and also slightly below the first roller in the series, to direct the coated tape base toward the right end of the drying chamber. As shown in Fig. 3, the uncoated but cleaned tape base 100' going to the coating machine overlaps slightly the coated tape base 100 as it advances toward the right end of the drying chamber. Before tracing further the progress of the tape base, the remainder of the coating machine will be described.

Feed hopper 370 and bottom support 372 (Figs. 11 and 12) are carried by platform 414 which is secured to a vertical support 420 attached to back side wall 220. The

bottom support is integrally secured to the platform. As l shown Vto better advantage in Fig. 16, its top surface is generally convex or arched in longitudinal contour 422, with a flattened intermediate portion 424. As shown in Fig. 18, the top of the bottom support is provided with an over-all channel 426, its side boundaries being defined by flanges 428 and 430. The width of the over-all channel is adapted to Yaccommodate the tape base, not snugly and not too loosely. The tape base slides easily through the channel. It does not move laterally from side to side; nor does it become bound between the flanges.

The top of the bottom support is also provided with a pair of side drainage troughs 432 and 434 adjacent the flanges and intermediate raised bearing portion 436 of the bottom support. As shown in Figs. 17 and 18, tape base- 100 is'in position in the channel, the bearing portion being sufficiently wide almost to extend from row 440 to row 442 of thesprocket holes. As will be described below, this arrangement permits excess coating material to run through the sprocket holes into the side drainage troughs'. lSince the troughs, like the top of the bottom support, are arched or convex longitudinally, the coating material flows away by gravity, and remains out of contact with the tapeA base.

Feed hopper 370 (Fig. 12) is secured to the free end of a lateral arm support 45t) pivotally supported at the other on a ball-bearing 452 in the upper end of a vertical support 454 attached to platform 414, so that4 the feed hopper can be raised or lowered, as desired, with respect to the bottom support.

To regulate the vertical height of the space between the feed hopper and the bottom support and to regulate the hopper horizontally with respect to the bottom support, several special features are employed. Thus, the hopper and the bottom support are anked by a fixed back block 456 (Fig. 1l) secured to platform 414 and a slidablefront block 453 resting on the platform. The front block ,is provided with a threaded lateral adjusting rod460 extending through a vertical arm 462 at the free end of the platform. Lock nuts 464 and 466 on the rod permit lateral adjustment of the rod and hence of the front block.

Secured to opposite sides of lateral' arm support 450 (Fig. l1) adjacent the hopper are lugs 468 and 470. A The f former lug (Fig. 14) is fitted with a vertical adjusting pin 472 having lock nuts 474 and 476 and a turning knob 478; all of which are adjustable with respect to fixed back block 456. The latter lug (Fig. 13) is fitted with a similar vertical adjusting pin 48) having lock nuts 482 and 484 and a turning knob 436, all of which are adjustable with respect to slid-able front block 458, the lower end of the pin fitting into a V-shaped notch 488 in the top of the block.

While the feed hopper may be raised and lowered by lifting, since lateral arm support 450 is pivoted, fine adjustment of the hopper with respect to the bottom support is obtained with the adjusting means just described. Vertical pins 472 and 480 are used to adjust the hopper vertically, and lateral rod 46) is used to adjust the hopper horizontally. In this manner the height of the gap or space between the hopper and the bottom support and the horizontal position of the hopper with respect to the bottom support may be accurately adjusted and then be locked to maintain their relative positions.

Now to examine the feed hopper itself in more detail. As shown more particularly in Figs. 16, 17 and 18, in cross-section the hopper is semi-elliptical inl shape, the elliptical front portion 496 facing the approaching tape base while the straight back portion 492 faces the receding coated tape base. rl`he elliptical portion is divided into an intermediate curved part 45,44 and two straight end parts 496 and 498, the former spanning the width of the tape base, between the two rows of sprocket holes, to be coated, and the latter ending just short of the two rows of sprocket holes to avoid coating of the areas between and immediately adjacent to the holes.

The cross-sectional feed hopper portions just described flare outwardly to form the upper or main body portion 50!) of the hopper. As shown in Fig. 11, one end of a tube 502 connects the upper portion of the hopper, while the other end is bent over an over-iiow container 564, resting on the top of the drying chamber, to catch excess coating material.

A supply vessel 506 with a removable cover S68 (Fig. 11) is supported in a saddle 510 on an upper platform 512 extending laterally from the top of Vetrical support 420. A conduit 514, with a valve 516, depends from the vessel into the feed hopper. A supply of finely divided magnetic coating material 52), such as a dispersion of magnetic oxide of iron, is maintained in the vessel. When.

valve 516 is opened the feed-hopper is filled to a level 522. Since it is well nigh impossible to regulate the valve to pass the precise amount of magnetic material.

required to coat the tape base, a slight excess is permitted to drop. It finds its way through tube 502 into container 504 and may be returned to the system, pref# erably after being dispersed specially in a fresh body of coating material to be supplied to vessel 566.

As already indicated, the space between feed hopper 370 and bottom support 372 is accurately adjusted to permit the deposition of a coating of magnetic material of desired thickness on the .'ipe base; after which the cleaned and preliminarily dried tape base 190 moves upwardly under advance roller 366 (Fig. 12), slides over the top of the bottom support, under the feed hopper, and is given a continuous coating 524 of the magnetic material. The freshly coated tape base 100" then passes around rollers 374 and 376 to, under and around second sprocket 292 (Figs. 2, 5 and 9) on the far end of'drive shaft 284. The coated tape base then passes back and forth in the drying chamber, progressively working its way, while being dried, toward the exit portion of the drying chamber; the lower right corner as one views Fig. 2. During this period of travel the tape base isy propelled in its path of travel by the ten driven sprocketsl and is ready to issue from the chamber as dried coated tape base 100'.

During its progress back and forth in the drying ma, chines, the tape base, it will be recalled, first passed over the top of the far end drive sprocket 290 on the far end of right cross drive shaft 284 at the back right-hand corner portion of the preliminary drying machine (Figs. 2, 4, and 9), to and through the coating machine and around its ve rollers 362, 364, 366, 374 and 376 (Figs. ll and l2), and back to, under and around the top of second far drive sprocket 292 on the cross drive shaft. From thence the tape base moves to the left to and aroundthe top of first roller 340 on the far end of left cross-shaft 330; then to the right back to, under and around lthe top of third drive sprocket 291.. on the right cross-shaft. By this time, the pattern of the back-andforth movement of the coated tape base is well established. It is one Vin which the uncoated side only of the tape base comes in contact with the sprockets and rollers, thus permitting the coating to dry and not to be injured by physical contact with any moving or fixed parts of the drying machines.

It is clear from the alternate arrangement of sprockets and rollers on the right cross-drive shaft and the complementary olf-set rollers on the left cross-shaft, that the coated tape continues to advance back and forth in the same general movement pattern. From drive sprocket 294 .the tape base returns to the next roller 340 in the series on lthe left cross-shaft, back to roller 310; thence another roller 340, roller 312, third roller 349, sprocket 296, fourthroller 340, roller 314, etc., until, as stated below, the tape base is dried and reaches the last near end sprocket Y308, von the right cross-driven shaft, at the right front side portion of the drying machine.

The back-and-forth movement of the coated tape base as it advances across the drying chamber may be regarded as a general helical movement. This is assured by the form kof structure employed. Thus, right crossdriveshaft 284 and left cross-shaft 33t) may be considered, in crossfsection as side members of a generally rectangular frame.4 The manner in which the sprockets and rollers of -shaft 264 are successively olf-set with respect to the rollers of shaft 330 assures a generally helical guide support and hence a helical course of travel, for the coated tape base, as it advances progressively across the `drying-chamber. The helical course may be made as long as desired and the coating is kept continuously out of contact with the frame, including sprockets and rollers.

Otherfforms of structure may be used to provide the helical guide support for the advancing coated tape base.

For example, in cross-section the support may be polygonal, circular, elliptical, etc. While the position of -the support in the instant case is fixed, the support as a whole ymay be rotated, say by a central shaft or other driving means.` What is important is that the path of travel ofthe coated tape base shall'be generally helical.

The detention period of the tape base in the drying chamber must be long enough to assure adequate drying of the coating. It is `dependent upon the suitable regulation of a'number of variables, such as the temperature andrate of progress of the heated air through the chamber; the length, width and height of the chamber; the number and spacing of the sprockets and rollers; the rate of travel of the Vtape base through the chamber; the viscosity and composition of the coating material; the thickness of the coating, etc. A few trial and 'error tests easily indicate suitable operating conditions.

Since the tape base passes back and forth in a zig-zag manner (Figs. 2 and 3), it is given a slight twist, particularly at the sprockets and rollers on the cross-shafts, to direct the moving tape base on a bias toward the next sprocket or Vroller in the path of travel, thus advancing the tape base gradually from the back side to the frontside of the drying chamber.v VWith a drying chamber of suitableflength the amount of twist is insuicient permanently to distort the tape base. This is particularly true of the moving picture type of magnetic sound recording tape base because it is quite narrow in width. The wider the -tape ibase, the greater, of course, is the amount of twist for a drying machine of given size; and, by the same token, the longer the drying chamber the less is the Winding device While a rplan view of the winding device is found in Fig. 2, it is detailed in Figs. 19-23. Drive shaft 284, Yit will be recalled, extends transversely of the right endof the heating chamber. The last or tenth drive sprocket 308, on the near end of the shaft, helps to propel the dried coated tape base through slot 53% in right end wall 21S of the heating chamber. Since the coated tape base passes around its lower portion, the sprocket rotates clockwise as one views Figs. 19 and 21.

Intermediate the slot and slightly above the sprocket is inside roller 532 mounted on the upper end of a depending bracket 534. The bracket is pivotally secured the end wall. The lower end of the bracket is pivotally connected to a lateral pull rod 538 extending through the wall a convenient distance. It is provided at its free end with a hand knob 540; compression spring 542 is attached at one end to the hand grip and at the other end to a collar 544 secured to the end wall. The spring functions normally to keep the anges of roller 532 in frictional engagement with the anges of drive sprocket 308, thus causing the roller to rotate in a counter-clockwise direction, again as one views Figs. 19 and 2l.

A curved guide plate 559, of sheet metal, is spaced between the flanges of and a short distance above the roller to provide a passageway for the tape base. plat'eis secured at its upper end to the end wall of the drying chamber. The lower end of the guide plate curves downwardly'towar'd the roller surface portion of the drive sprocket, vintermediate its anges, but above the normal path of travel of the coated tape base. As shown in Fig. 2l particularly, the tape base normally is not in contact with the guide plate. The guide plate, however, is useful in threading the forward end of the tape base when beginning operations. It also helps to keep the forward end of the tape base from springing back into the drying chamber, more especially when a spliced portion (to be described below) is cut therefrom as it issues from the chamber. The plate also keeps the adjacent coated tape base from twisting and Wrinkling.

Spring 542 normally is under suficient compression to keep the flanges of the roller in tight engagement with the flanges of the drive sprocket. This assures continuous rotation of the roller which helps to propel the tape base forwardly. Such engagement of the flanges, however, may be broken, when desired, by pushing on hand knob 540.

Closely associated with inside roller 532 is an outside roller 552, adjacent slot 5343, mounted in journals 554 attached to the outside of right end wall 21S. It helps to guide the dried tape base into the winding zone for rolling onto reels and also to divert temporarily, when desired, unrolled tape base into a container 569 directly below the the roller; particularly when a spliced section of the tape base isv to be removed, as will be described in some detail below.

A rearwardly extending front side arm 562 (Figs. 2,

19 and 20) is secured to front side wall 224 of the drying' chamber. A journal 564, tted with a shaft 566, is attached to the top of the arm a convenient distance from the drying chamber. A pulley 563 is' integrally secured to the near end of the shaft. As in the case of shafts 66 and 68 (Figs. 2, 4 and 8), the other end of shaft 566 is fitted with a fixed half-reel 579 provided with tapered end 572 adapted to t into hub 574, like hubs 92 and 94, of standard design. The hubs used with the winding and unwinding devices are interchangeable, being adapted to lit on any of the half-reels.

As shown to better advantage in Fig. 20, transverse drive shaft 284 in the right end of the drying chamber terminates exteriorly in a drive pulley 580, a belt 582 The guide 1 1 ts over that pulley as well as pulley 563 on shaft S66. Rotation of the drive shaft therefore rotates the latter pulley; thus rotating half-reel 570. The Vend of dried tape base 160'" issuing through slot 530 in the right end of the drying chamber is secured to hub 574, and is rolled thereon.

A braking or tensioning device 586 (Figs. 19, 2O and 23) is associated with the lower mid-portion of the drive belt in order to slow down the hub as its roll of tape base increases in diameter. Unlike the automatic tension braking device associated withthe unwinding device (Figs. 2, 4Vand 5), the present one is hand-operated. As shown in Fig. 23, it includes aiixed lateral block 538, secured to the top of extension arm 56T., through which depends a movable vertical block 590; and into the lower end of which fits a lateral stub shaft 592 having a brake pulley 594 mounted thereon. Extending through a threaded hole in the xed lateral block is a vertical threaded rod 596, to the upper end of which is fixed a hand wheel 598 having an annular flange 600 iitting into a complementary groove in the adjacent side of the depending movable vertical block. The hand wheel can be turned to move the vertical block, and hence the brake pulley, up or down, Yas required to decrease or increase its braking action on belt 582. As the roll of tape base on the half reel builds up, the hand wheel is turned from time to time to increase the brake action on the reel and hence to keep under control the tendency of the reel unduly to increase its momentum.

To facilitate operations, an empty hub 604 (Fig. 19) is kept close at hand. In the instant construction it is temporarily mounted on tapered end 60S of a half-reel, 606, suitably supported on rearwardly extending front side arm 562. When hub 574 and its roll of tape base are removed from half-reel 570, empty hub 604 is quickly removed from its tapered shaft end 608 of half-reel 606 and mounted on tapered end 372 of half-reel 570. The forward end of the tape base issuing from the drying chamber is attached to the empty hub, and winding of a new roll proceeds as before.

Splicing device Returning to Figs. 2, 4 and 5, splicing zone G is shown directly above half-reel 80 in unwinding zone A, adjacent the cleaning device. An enlarged detail of splicing device 52 is given in Fig. 24. The splicing device includes a vertically extending L-shaped support 610 attached at its lower end to rearwardly extending back side arm 60. A splicing platform 612 is pivotally secured to the upper end of the L-support. 1t is adapted to swing (Fig. 4) into a forward working position and into (see dotted outline, Fig. 24) a rearward position when not in use. The platform is in the shape of a channel 614, with side flanges 616 and 61S, and a pair of spaced sprocket-hole teeth 620 and 622. The width of the channel is such as to accommodate easily, not tightly or too loosely, the width of the pieces of tape base to be spliced. The spacing and size of the teeth are such as to t easily into two superposed pairs of opposed sprocket holes in the pieces of tape base to be spliced. The channel itself helps to align the sprocket holes of the pieces of tape base being spliced. If the vtape base is not of the moving picture film type, the sprocket teeth in the platform are omitted. The channel itself is then adequate to align the tape base ends for splicing.

For the splicing operation itself, reference may be made to Figs. 25-31, in addition to Fig. 4. As shown in dotted outline in the latter figure, tail or rearward end v630 of tape base 100, at the end of its roll, previously on hub 92 on half-reel 80, is to be spliced to forward end 632. of tape 'oase 102, on the roll on hub 94 on half-reel 82, about to be unwouncl for processing.

A previously prepared (Fig. 25) laminated splicing band 634 is employed. It includes an inside adhesive band 636, with adhesive surfaces on both sides, protected temporarily by a lower removable cover 638 and an upper j removable cover 640. y

As shown in Fig. 26, forward end 632 of tape base 102 is placed in channel 614 of splicing platform 612, in its horizontal or working position, being locked therein temporarily by sprocket teeth 620 and 622. Lowervcover 638 is removed from adhesive band 636 and the band is placed on the top of forward end 632 of the tape base, intermediate its two rows 642 and 644 of sprocket holes.

The combined forward tips 646 (Fig. 26) of the tape base, adhesive band 636 and upper cover 640 are then sharply cut otf, say with shears, along the left end edge of the splicing platform, as shown to the left of Fig. 26. This assures (Fig. 27) a tight adhesive contact between the forward end of the tape base and the adhesive band; which is highly desirable in Stringing or feeding forward end 632 of tape base 102 through the cleaning device, the preliminary drying, the coating and the final drying machines. Since there is no loose end of the spliced assembly to catch against a guide, sprocket, roller o1' other part of the apparatus, the spliced portion glides smoothly over all parts it engages physically. Upper cover 640 is stripped olf the top of adhesive band 636. The preliminary splicing operation with tape base 102, just described, takes place before tape base is completely unrolled from its hub, because the operator has not got much time for, and, consequently, must move quickly during, the next splicing operation while tape base 100 continues to be processed without any interruption.

. The operator watches closely the nal unwinding of tape base 100from its hub on half-reel 80 because he does not want to lose control of its tail or rearward end 630. If the free tail end of the tape base should advance through the cleaning device into the drying machine, he would have to string or feed manually forward end 632 of tape base 102 through the apparatus. He avoids this laborious and time consuming job by grasping the unwound tape base near the roll when only a few more turns, which are wrinkled, undesired, and discarded, remain on the roll, cutting the tape base while holding the resulting free tail or rearward end of tape base 100 as it leaves its hub, raises and pulls it over the top of the splicing platform, with its sprocket holes engaging the sprocket teeth of the splicing platform, places and presses the tail end of the tape base on the top of adhesive band 634 and the forward end of tape base 102, as shown in Figs. 28 and 29. The free extreme rearward end of tapeY base 100 is permitted to extend beyond the adhesive band, as shown to the right of Figs. 30 and 31 (after coating), because it does not materially interfere with the smooth progress ofvspliced portion 650 through the remainder of the apparatus.

When tail end 630 of tape base 100 is grasped, raised, pulled and placed over the splicing platform (Fig. 4), bottom rollers 126 and 128 and their side supportsV 130 and 132 are raised'upwardly in tank 100 of cleaning device 42, toward the position 138 shown in dotted outline. The raising of the bottom rollers is due to the pulling action of tape base 100 as a whole as it is advanced forwardly through the apparatus by the driving means and in part to the rearwardly pulling action of the operator as he raises and places the tail end of the tape base onto the splicing platform.

In any event (Fig. 4), as the bottom rollers and the tape base loops rise in the body of cleaning liquid, accumulated slack in the loops is taken up and the operator is given time in which to complete the splicing operation. The loops attain a predetermined maximum length to provide the desired amount of slack.

While the loops and hence the slack may be made long enough to permit enough time toV complete the entire splicing operation at this stage, we prefer to proceed in two stages in the manner described.

The slack-producing zone need not be in the cleaning Zone, but the present arrangement has the advantage that When splice 650 is completed, the operator removes empty hub 92 from half-reel 80, raises the spliced ends of tape base 100 andktape base 102, frees them of the splicing platform, permits the resulting slack of tape base to go into the cleaning device, and moves full hub 94 and its roll of tape base 102 from half-reel 82 onto half-reel 80. l

Since the cleaning liquid may impair the bond between the adhesive band and the tape base ends attached thereto, for example, by dissolving or softening the adhesive, it is advantageous not to bring the splice in contact with the liquid. To this end the operator permits the loops of slack tape base to rise above liquid level 142 (see dotted'outline 138 of bottom rollers 126 and 128 Fig. 4), and then permits the splice to pass completely` around the `lower rollers on its way to the air squeegees. He can do this by controlling the rate at which the splice is fed to and through the slack-producing zone, so that the cleaning liquid is entirely by-passed. While the section of the tape base thus by-passed is not cleaned, the amount is negligible and, in any event, usually is not used.

Due to the weight of bottom rollers 126 and 128 (Fig. 4), they sink by gravity to the bottom of the body of cleaning liquid in tank 100, exerting an increased pull on the new roll of tape base and its hub and thereby increasing temporarily the speed of rotation of half-reel 80 against the brake-action of brake discs 70 and 72, as well as restoring the loops of tape base to their former length and hence providing the required slack for the next splicing operation. In a few moments tape base 102 unwinds at the same rate the remainder of tape base 100 advances through the coating and drying machines. As this occurs the forward end of tape base 102 is pulled, strung or fed automatically and continuously through the cleaning device, the preliminary drying machine, the coating and final drying machines to the winding device, without any loss of time.

Such continuity of movement of tape base through the apparatus as a whole is of vital importance. It assures ecient, rapid, production of coated tape base. If the continuity is broken, for example, by stopping the motor, diiculties promptly arise in the coating zone. The coating material continues to ow from the feed hopper; spreading itself all over the immediate stationary tape base; the bottom support and adjacent portions of the coating machine; etc. Time and labor are required to clean the resulting mess; the coating on that portion of the tape base is rendered useless; tape base must be passed through the coatnig machine until normal coating conditions are re-established; a substantial amount of the tape base is rendered useless; it must be located and cut out later; the new ends must be spliced; the over-all linear length of the properly coated tape base must be determined; etc. All in all, the breaking of the continuity of passage of tape base through the apparatus is vexatious and costly. Fortunately, the present improvements permit operations to be continuous and such diculties are avoided.

Since the slack loop or loops of tape base help to establish that continuity, a suitable linear length must be selected. That length depends on the speed of travel of the tape base through the apparatus and the time required by the operator to splice the tail end of the unwound roll to the forward end of the next roll of tape base. As a safety factor, excess slack is provided, so that the operator may be certain to complete the splicing operation.

The spliced portion between the two rolls, moreover, is in such condition that it passes easily through the coating zone. Dueto the adjustability of the bottom support and the feed hopper with respect to each other,

thessplicedV portiony passes between them without any diiculty, thefeed hopper rising automatically to permit `thespiice to pass thereunder.

A fresh roll of tape base is mounted on half-reel 82 in readiness for the-same type of procedure.` Its forward end .is brought over the top of the splicing platform and when it leaves hub 94. I

The operator may soon divert his attention to Winding device 50. He can tell by observing the size of the roll of coated tape base on half-reel S70 when it is about time to expect spliced portion 650 of tape bases 100 and 102 to issue from the drying chamber. To this end he also looks through the top windows of the drying chamber of the final drying machine to note and trace the progress of the spliced portion toward the discharge end ofthe drying chamber. it may be assumed that tape base 102 is being processed at this stage, although the drawings illustrate this with respect to tape base 100.

He turns (Fig. 19) hand-wheel 598 on braking device 536 to adjust the braking or slippage action of belt 582 and stands in readiness with a pair of shears. When the spliced portion issues through slot 530 in the discharge end of the inal drying chamber he quickly cuts away and discards the entire spliced portion (Figs. 30 and 31). He drops the forward portion of tape base 102 into container 560, Where the oncoming dried, coated tape base continues to collect While he removes wound roll of tape base 100'" and its hub 574 from half-reel 570; and while he removes empty hub 604 from its half-reel 606 and mounts it on half-reel 570. He lifts the forward end of dried, coated tape base 102'" from container 560, attaches it to empty hub 604- for winding into a new roll, as before. Due to the decrease in braking action, slack tape base 10 in the container is Wound rapidly onto the hub, after which the operator may again turn, as he continues to do from time to time, hand-wheel 598 to regulate the rate of winding of the roll in accordance with the rate of issue of coated tape base from the drying chamber. Another empty hub is mounted on half-reel 606 in readiness for another such procedure when tape base 102'" is wound into its roll.

Except for the small pieces of tape base in the discarded spliced portions, each roll of coated tape base is as long as it was when uncoated. That is, each roll of fresh or uncoated tape base is processed into its own roll of coated tape base. The spliced portion between rolls is only a temporary expedient, used automatically to cause tape base in a succeeding roll to follow the same path of travel taken by tape base from a preceding roll.

It will thus be seen that the method and apparatus of the present application provide a number of novel and highly useful improvements. To those skilled in this art, it will be clear also that the above description is only by way of illustrating a practice of the invention, and that a number of useful modications likewise may be employed in such practice.

We claim:

In the method of producing blank magnetic sound recording tape wherein an elongated piece of tape base is unwound from a roll of the same n an unwinding zone, passed while under tension through a coating zone and a drying zone and wound into a roll in a winding zone and the forward end of a subsequent rollof tape base to be processed ,is spliced to the tail end of the roll of tape base being processed before such tail end reaches the coating zone; the improvement which comprises passing the unwound tape base at a continuous normal rate of speed through the coating and drying zones, accumulating a predetermined length of unwound advancing slack tape base wholly by gravity in a slack-producing zone in ad- For purposes of discussionvance'of "the'coating zone, the slack being accumulated at least in part as a continuously forming and depending generally U-shaped loop. of given maximum height, With the`tops of the open legs of the loop in fixed locations but with the bottom closed leg portion of the loop free to riseA and fall as required, continuing the Unwin-ding of the roll of tape base until its tail end leaves the roll, securing an adhesive band to the forward end of the roll of tape base next to be processed, cutting ol sharply the forward tip portion of the combined adhesive band and tape base secured thereto, whereby a tight joint between the two that will slide easily without damage thereto is obtained in they line of cutting, securing the tail end of the roll of tape base beingprocessed to the opposite side of the adhesive band, taking up simultaneously suicient ac- 15 cumulated tape base slack in ,theV slack-producing zone fromL the rst roll to permit the advancing tape base from that roll Vto continue through the coating and drying zonesv at its normalV speed of travel, the height of the U-shaped loop being reduced as the slack is taken up and the bottom 20 2,435,376

portion of the loop rises ,duringthe splicing operation, unwinding the second roll of tape base in the unwinding zone after the splicing operation in completed, and accelerating temporarily the rate of unwinding of the second roll until the bottomportion of the loop falls to its former position and the loop as a Whole is restoredto its normal height in the slack-producing zone in readiness for splicing the tail end ofthe second roll of tape base to the forward end of th'enext roll of` tape base in the series 10 similarly to be processed,

References Cited in the tile of this patent UNITED STATES PATENTSA 1,261,056 PfohlA Apr. 2, 1918YV 1,552,421 Cumfer Sept. 8, 1925 1,605,842 Jones Nov. 2, 1926 2,104,774 Scott Jan. 1l, 1938 2,377,971 Roesen June 12, 1945 Wilcoxon Feb. 3, 1948 

